Tool holding systems can be provided with a clamping portion having a clamping bore for clampingly receiving a cutting insert therein. Typically, in rotary cutting tools, the clamping bore is formed in a clamping sleeve that undergoes an inward radial displacement (i.e. diameter shrinkage) thereby clampingly engaging the cutting insert located in the clamping bore. The inward radial displacement can be actuated by a tightening member, such as a tightening nut.
In some such tool holding systems said diameter shrinkage can be achieved by providing eccentric surface(s) on the clamping sleeve that are urged radially inwardly by tightening of the tightening member.
In some other such tool holding systems the clamping sleeve can be formed by a conical collet, for example, a standard ER collet. Examples of such tool holding systems, are disclosed in, for example, U.S. Pat. Nos. 4,699,388 and 8,118,312. Optionally, to allow precise alignment of the collet, the collet can be detachably connected to an annular collet ring that is rotatably connected to the tightening nut. Examples of such tool holding systems are disclosed in, for example, U.S. Pat. Nos. 5,522,605 and 5,911,421, where the collet ring is rotatably connected to the tightening nut via ball bearings.